The present invention relates to a specific fused polynuclear (or polycyclic) compound and an organic luminescence device using the fused polynuclear compound.
An organic luminescence device is a device such that a thin film containing a fluorescent organic compound is sandwiched between an anode and a cathode, and holes nd electrons are injected from the anode and the cathode, respectively, into the fluorescent organic compound layer to generate excitons which emit light at the time of being returned to a ground state.
More specifically, according to Kodak""s study (Appl. Phys. Lett.xe2x80x9d, 51,913 (1987)), when a voltage of ca. 10 volts is applied to a function separation-type organic luminescence device including two layers of an aluminum quinolinol complex (as electron transport and luminescence material) and a triphenylamine derivative (as hole transport material) disposed between an anode of ITO (indium tin oxide) and a cathode of a magnesium-silver alloy, an emission luminance of ca. 1000 cd/m2 is obtained. Related patents thereof are, e.g., U.S. Pat. Nos. 4,539,507; 4,720,432; and 4,885,211.
Further, it is possible to effect luminescence ranging from ultraviolet region to infrared region by appropriately changing the species of a fluorescent organic compound used. In recent years, studies on various fluorescent organic compounds have been made extensively as, e.g., described in U.S. Pat. Nos. 5,151,629 5,409,783; and 5,382,477; and Japanese Laid-Open Patent Application (JP-A) Nos. 2-247278 (corr. to U.S. Pat. Nos. 5,130,603 and 6,093,864); 3-255190 (corr. to U.S. Pat. No. 5,227,252); 5-202356: 9-202878; and 9-227576.
In addition to the above-mentioned organic luminescence devices using low-molecular weight materials, an organic luminescence device using a conjugated system polymer has been reported by a research group of Kenbridge University (xe2x80x9cNaturexe2x80x9d, 347,539 (1990)). According to this report, by forming a single layer of PPV (polyphenylenevinylene) by means of wet coating, luminescence from the layer has been confirmed.
Related patents as to organic luminescence devices using conjugated system polymers may include: U.S. Pat. Nos. 5,247,190; 5,514,878; and 5,672,678; JP-A 4-145192 (corr. to U.S. Pat. Nos. 5,317,169 and 5,726,457) and JP-A 5-247460.
As described above, recent progress of the organic luminescence devices is noticeable. More specifically, it is possible to realize a thin and light-weight luminescence device allowing high luminance at low applied voltage, variety of emission wavelength and high-speed responsiveness, thus suggesting possibilities of application to various uses.
However, the organic luminescence devices are required to exhibit further improved performances such as light output at high luminance and high conversion efficiency. Further, the organic luminescence devices have been accompanied with problems in terms of durability such as a change in luminance with time due to continuous use for a long time, and a deterioration (e.g., an occurrence of dark spots due to leakage of current) by ambient gas containing oxygen or by humidity. Moreover, in the case where the organic luminescence devices are applied to full-color displays, it is necessary to realize luminance of red (R), green (G) and blue (B) with good color purities but resultant color purities have been insufficient as yet.
As fluorescent organic compounds for use in an electron transport layer and/or a luminescence layer, a large number of aromatic compounds or fused polynuclear aromatic compounds have been proposed as described in, e.g., JP-A 4-68076, 5-32966, 6-228552, 6-240244, 7-109454, 8-311442 (corr. to U.S. Pat. No. 6,203,933), 9-241629, 2000-26334, and 2000-268964. However, resultant emission luminances and durabilities have been still insufficient.
A principal object of the present invention is to provide an organic luminescence device having solved the above-mentioned problems.
A specific object of the present invention is to provide an organic luminescence device capable of effecting output of light with very high efficiency and luminance by using a specific fused polynuclear aromatic compound.
Another object of the present invention is to provide an organic luminescence device having a high durability.
A further object of the present invention is to provide an organic luminescence device which can be prepared readily and relatively inexpensively.
According to the present invention, there is provided an organic luminescence device, comprising:
a pair of an anode and a cathode, and
at least one organic luminescence function layer disposed between the anode and the cathode, wherein
at least one organic luminescence function layer described above comprises a layer comprising at least ohe species of a fused polynuclear compound characterized by a substituted benzene structure having at least two fused polynuclear aromatic or heterocyclic groups as substituents.
The fused polynuclear compound used in the present invention is represented by any one of the following formulas (I) to (VII): 
In the above formulas (I) to (VII), R1 to R18 independently denote hydrogen atom, an alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted amino group or cyano group; and Ar1 to Ar24 independently denote a substituted or unsubstituted fused polynuclear aromatic group or a substituted or unsubstituted fused polynuclear heterocyclic group.
In the present invention, Ar1 to Ar24 in the above-mentioned formulas (I) to (VII) may preferably denote a substituted or unsubstituted fused polynuclear group comprising at least three fused benzene rings or at least four fused benzene rings, more preferably be a fused polynuclear group represented by any one of the following formulas (VIII) to (XIII). 
In the above formulas (VIII) to (XIII), R1 to R26 independently denote hydrogen atom, an aralkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heterocyclic group, a substituted amino group or cyano group.
In the present invention, when the above-mentioned at least one organic luminescence function layer comprises an electron transport layer and or a luminescence layer, the electron transport layer or luminescence layer may preferably comprise a fused polynuclear compound represented by any one of the formulas (I) to (VII). In this case, in a more preferred embodiment, the luminescence layer comprises a fused polynuclear compound represented by any one of the formulas (I) to (VII) and a compound represented by the following formula: 
Further, when the above-mentioned at least one organic luminescence function layer comprises an electron transport layer and or a luminescence layer, the electron transport layer may preferably comprise a hole transporting material and a yellow luminescent material, and said luminescence later may preferably comprise a fused polynuclear compound represented by any one of the formulas (I) to (VII) and a compound represented by the following formula: 
The fused polynuclear compound used in the prevent invention may preferably be represented by any one of the following formulas: 
These and other objects, features and advantages of the present invention will become more apparent upon a consideration of the following description of the preferred embodiments of the present invention taken in conjunction with the accompanying drawings.